Desalination-Coupled (photo)Electrocatalysis for Production of Value-Added Chemicals

Abstract

Water and energy are the most essential elements for a sustainable human society. They are strongly interdependent because energy production requires a significant amount of water, while the production, processing, distribution, and end-use of water requires large energy inputs. Several water-energy nexus technologies have emerged, including PV-electrolysis and microbial desalination. Herein, we propose a hybrid process that is driven by sunlight and boosted by electrodialysis. A sunlit inorganic photoanode initiates the desalination of saline water in the middle cell. As the chloride in the middle cell moves to the anode cell, the wastewater (WW) treatment is boosted by reactive chlorine species (RCS) generated via the reaction with photogenerated holes. An increase in the electrical conductivity in the anode cell further enhances the photoelectrocatalytic (PEC) WW treatment. Upon a potential bias, various value-added chemicals (H2 via water reduction, H2O2 via O2 reduction, and HCOOH via CO2 reduction) are produced in the cathode cell, and the production of the chemical is enhanced as the desalination proceeds because of sodium enrichment (i.e., conductivity increase). The uniqueness and advantages of this hybrid process include its broad range of operating conditions (virtually the entire pH range) and the wide variety of inorganic and organic substrates that can be treated (i.e., aquatic pollutants), while desalination boosts the overall operation and chloride catalyzes the anodic reaction, which in turn facilitates the desalination. Although tested as a proof-of-concept, the present technology opens up a novel field involving a sunlight-water-energy nexus, promising high efficiency desalination and the desalination-boosted remediation of water with simultaneous production of value-added chemicals.

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Identifiers

DOI

10.1149/ma2024-02493537mtgabs

Journal

ECS Meeting Abstracts

Year

2024